Plasmodium sporozoites migrate through and invade different cell types in the mosquito vector and vertebrate host. At the end of their journey they transform into exo-erythrocytic forms within a hepatocyte. Irradiated sporozoites induce protective immunity against malaria and therefore it is of great importance to identify sporozoite and EEF proteins entering the host hepatocyte. However, little is known about secreted and surface proteins of Plasmodium sporozoites and their involvement in sporozoite-host cell interactions. No information is available about proteins involved in the cross talk of the intracellular EEF with the host hepatocyte. The overall objective of this proposal is the characterization of newly identified sporozoite-expressed and EEF-expressed proteins and their role in host-parasite interactions and the identification of additional molecules that could be important for these interactions. This will lead to a more complete understanding of the parasites complex biology but might also identify new potential candidates for inclusion into a pre-erythrocytic subunit vaccine and targets for transmission blocking strategies.